Re: 3 blade props versus 4 or 5
The prop design has is affected by surface area. If you have more surface you have the potential to push more water. If you have more surface you also have more drag. With higher pitch it is harder to get the surface area you need with few blades so very high pitch props may need more than 3 blades and very low pitch props may be less effective with more blades. However each blade affects the flow around the next so you want fewer to be more efficient but you also want a shorter chord length on each blade to be efficient.
The shortest answer is you might get more hole shot acceleration with more blades and you might get more speed with fewer blades but it is variable because of the wide variety of prop designs, gear ratios and engine outputs, and hull design.
